<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .div1{
            background: skyblue;
            overflow: hidden;
        }
        .zi{
            margin-top: 20px;
            height: 100px;
            width: 100px;
            background: blue;
            
        }
        .hidden {
            height: 100px;
            background: skyblue;
            overflow: hidden;
        }
        .box {
            overflow: hidden;
            zoom: 1;
        }
        .box div{
            float: left;
            width: 100px;
            height: 100px;
        }
        .box1 {
            background-color: yellow;
        }
        .box2{
            background-color: slateblue;
        }
        .wai{
            width: 300px;
            height: 200px;
            background: skyblue;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="box1">
            第一个子元素
        </div>
        <div class="box2">
            第二个子元素
        </div>
    </div>
    <div class="wai">
        外部区域
    </div>

    <!-- <div class="div1">
        <div class="zi">
            子元素
        </div>
    </div> -->
    <!-- <div class="hidden">
        <p>超出的内容隐藏</p>
        <p>超出的内容隐藏</p>
        <p>超出的内容隐藏</p>
        <p>超出的内容隐藏</p>
        <p>超出的内容隐藏</p>
    </div> -->
</body>
</html>